Saturday, May 21, 2011

Endemic-In-Waiting: Western White-naped Honeyeater

UPDATE: This species was renamed Gilbert's Honeyeaterin the IOC list from v5.2, and the same name was adopted by eBird/Clements when split in 2015.As we wait in post-C&B limbo to discover which body will replace Christidis & Boles [1] as the official arbiters of the Australian list, it appears almost certain that the next revision – by whoever – will split the western form of the White-naped Honeyeater (Melithreptus lunatus) as M. chloropsis. This change has already been adopted by the influential IOC World Bird List from v2.6 (Oct 23 2010) [2] and restores the species described and named by Gould himself in 1848 [3].

Both Gould and modern taxonomists cite the western form’s larger size, longer and thicker bill, thicker black margin around chin, and different colouration of the bare skin above the eye, which is bright red in lunatus but white to very pale blue-green in chloropsis (Latin for green-eyed). In support of re-splitting the species, a recent molecular analysis by Toon et al. (2010) [4] has demonstrated the two are paraphyletic, meaning that M. lunatus is more closely related to another species (the Black-headed Honeyeater M. affinis of Tasmania) than it is to its previously-alleged subspecies M. l. chloropsis. [Incidentally, Toon et al. found surprisingly “shallow” genetic differences in M. brevirostris, so I don’t think we’ll be seeing the elevation to species of Western Brown-headed Honeyeater leucogenys any time soon].

A Western White-naped Honeyeater, Melithreptus chloropsis, from marginal jarrah/karri forest at Donnelly River (near Bridgetown).

An interesting footnote to the taxonomy is that two subspecies of Western White-naped were once recognised, ‘green-eyed’ chloropsis in drier areas north and inland of Perth, and a south-coast form whitlocki with ‘chalky-white’ supraorbital skin, the type being from Wilson’s Inlet. Eventually it was realised (attributed to Mees 1964 [5]) that the bird is essentially white-eyed across its range with a greater bluish or blue-green tint in young birds, and that some green or blue tint also occurs in greyish bare skin below the eye. However Mees did not specify his sample or methods, and Gould seemed certain the eye skin is “…greenish white in some, in others pale wine-yellow” [3], so one wonders whether supraorbital colour may have varied in the northern or tuart forest populations which are much reduced since settlement.

The bad news from the White-naped split is that the IOC have revived Gould’s original name, the “Swan River Honeyeater”, their footnotes [2] stating:
Swan River Honeyeater preferred English name over long Western White-naped Honeyeater (and change to Eastern White-naped Honeyeater).
This decision has been viewed with bemusement by WA locals, given that the Swan River, in fact much of Swan coastal plain near Perth, is now almost the last place you would expect to find the bird. Its typical habitat is the denser jarrah/marri and wandoo woodlands of the Darling Ranges and Wheatbelt (through which the Avon, not the Swan, River flows) and sclerophyll forest throughout the lower South-west. Although it was previously recorded in tuart forest in the western parts of the Swan coastal plain, and was apparently “quite abundant” in Crawley in the 1890s [6], it was already becoming rare in the early 20th century, for example:

Hill (1904) on the Swan at Guildford [7]: “Have seen two or three birds only, both in thickish timber”

Serventy (1922) at home in Maddington [8] : “seen…but rarely”

Serventy (1948) Birds of the Swan River District [9]: “On the coastal plain it is only found in the tuart forest, but it has largely disappeared from there in recent years.”

Today it is effectively extinct from remnant coastal tuart forest from Perth to Bunbury, and in the Swan River area is, at best, an occasional autumn-winter visitor.

It would be interesting to know whether Gould did collect his bird near the Swan [UPDATE: this appears likely, probably by John Gilbert near modern-day King's Park], or whether he applied the name “Swan River Honeyeater” only in terms of the broader colony or region; the tag on the type specimen is no more specific than ‘Western Australia’, and “Hab: Western Australia” is the amusing extent of the distribution detail given in Gould’s monograph. In any case, his misnomer seems to have quickly fallen out of favour, as by the early 1900’s the name “Western White-naped Honeyeater” was already in common scientific usage for M. chloropsis; for example by Carter (1902) [10] and Milligan (1903) [11]. The same name was recommended in Mathews’ [12] revision to subspecies (ie. M. lunatus chloropsis) in 1912 (Mathews also listed a Southern White-naped Honeyeater M. l. adelaidensis, White-eyed Honeyeater for M. l. whitlocki, and the wonderful-sounding Gay Honeyeater for the obscure M. l. vinitinctus of North Qld.)

A Western White-naped Honeyeater from Denmark on the south coast. According to the old taxonomy, this should be close to the type location for M. l. whitlocki, with chalky white not pale blue-green supraorbital skin.

WA Museum ornithologists re-elevated chloropsis to full species level in Ron Johnstone’s 2001 WA Checklist [13] and Johnstone & Storr’s 2004 Handbook [14]. Before the ink had even dried, the name Western White-naped Honeyeater M. chloropsis was once again appearing in local scientific publications and environmental reports; for example Williams (2001) [15]. Given this published scientific usage of the name over more than a century, it seems absurd for the IOC to revive an ancient Gouldian clanger simply because it’s one syllable shorter! After all, as some wag commented on birding-aus, we don’t talk about Lunulated Honeyeaters (Gould’s name for M. lunatus) or the Swallow Dicaeum. Nor, indeed, such beauties as the Plain-coloured Pachycephala, Tricoloured Ephthianura, Ocellated Leipoa, or Azure-breasted Porphyrio. Latin scientific names have strict rules of precedence; common English names of course do not.

If the length of the name is the problem, it could perhaps be shortened to “Western Honeyeater” as was pre-empted in the 2nd edition of Slater’s guide [16], and as occurred when Western Wattlebird was split. Or perhaps use Mathews’ “White-eyed Honeyeater” from the southern form ‘whitlocki’ (though perhaps “White-eyed” wouldn’t sit well with the specific name chloropsis). Or Marri Honeyeater, as marri are one of their preferred trees. Or even Blackwood River Honeyeater - whilst a lesser known river, at least the honeyeater would be common along most of it's length! But please, not Swan River Honeyeater!

A young Western White-naped Honeyeater near Denmark. Juveniles could be mistaken for Brown-headed Honeyeater, but note more obvious pale nape band, lack of (or incomplete) eye-ring, greenish wing, and very clean white underparts.

If you would like to see the soon-to-be M. chloropsis, the best places close to Perth would NOT include the Swan River – try the Darling Range in jarrah forest from Carmel to Wungong. Sites in Birding Sites around Perth [17] which list the species as regular include Douglas Rd (cnr Canning Mills Rd) and Stony Brook (off Coventry Rd Roleystone). However, it is more common further afield in the wetter karri regions from Pemberton to Denmark, or the Stirling Ranges. It can also be rather common in some wandoo areas, for example Berry Brow Rd behind Bakers Hill.

An active bird, the Western White-naped Honeyeater spends a lot of time upside down as it as it gleans for insects and lerps amongst eucalypt foliage and branches.

2 comments:

Thanks for the record Anonymous. As noted above this species (now called Gilbert's Honeyeater) does occur infrequently in the Perth foothills close to the Darling scarp, possibly as part of minor seasonal movements in autumn-winter. But it no longer occurs across greater Perth metro in association with tuart forest, as it once did.